Always tech-savvy, Ballard started tracking his health with gadgets like glucose monitors, pedometers and heart rate monitors to see if he could detect anything that might explain why his ticker would suddenly start racing.

He got more serious last September, buying himself a $200 portable heart monitor built into a smartphone case to check his rhythms during palpitations or after exercise. Armed with a textbook on EKG interpretation, the 32-year-old nutrition student at California State University-Long Beach correctly diagnosed himself with Wolff-Parkinson-White syndrome, characterized by abnormal electrical activity in the heart.

This kind of technology "will really change the face of medicine," said Ballard, who hopes to attend medical school. "We'll have all this data and be able to get at the root of problems more efficiently."

Plus, he said, it motivates people. "When you have a device in your hand that can give you immediate feedback, it really changes your perspective."

More and more, doctors and other medical professionals agree.

Across the country, physicians and other providers are using new technologies to gather day-to-day information about their patients' conditions. And patients are using these tools to take greater charge of their own health.

Already, mobile apps, scales and activity trackers beam data they collect to the cloud for use by doctors and hospitals. Insurance and electronic medical records companies are investing in and partnering with tech outfits to encourage consumers to use activity- and health-tracking tools and upload their data.

Start-ups across the country are creating gadgets such as pill boxes that can monitor whether patients are taking their meds and under-the-mattress sensors that measure heart rate, breathing and movement.

At the Cardiovascular Medical Group of Southern California, where Ballard is being treated, cardiologist Ronald Karlsberg has become a big fan of the AliveCor portable heart monitor used by Ballard.

"It's a milestone for patient care," he said.

Many medical professionals have been slow to embrace the concept of patient-generated data — partly because they are skeptical of information they don't collect themselves. Some are leery of consumer-grade apps and gadgets that aren't approved by the U.S. Food and Drug Administration, which regulates medical devices.

Other doctors and other patient advocates are concerned that Internet-based systems aren't secure and that patient privacy might be breached.

But there are signs that resistance to patient-generated data is eroding.

Last month, Practice Fusion — the fourth-largest vendor of electronic medical records in the country, according to Bloomberg Businessweek — announced a partnership with AliveCor Inc. and Diasend, an online diabetes-management system. When patients approve sharing data from these FDA-approved services, their information will start flowing into their medical records.

Dr. Eric Topol, a cardiologist at the Scripps Clinic in San Diego, knows without even seeing a patient whether his heart is racing or his blood pressure soaring. Topol's patients send him screenshots of their AliveCor data as part of a clinical trial — a somewhat clunky process, for now, but better than waiting for an office visit.

"It's the real deal of what's going on in their world from a medical standpoint," said Topol. "The integration of that with the classical medical record is vital."

Companies like AliveCor and Diasend require FDA clearance for medical use because they provide diagnostic services.

But other devices — like Nike+ FuelBand and Fitbit, which work essentially like pedometers, are meant to foster healthful habits. For now, that distinction saves these companies from the drawn-out and expensive process of applying for FDA approval.

A roadblock to making all this patient-generated information medically relevant is it's in silos controlled by the companies that collect it. Plus, analyzing it can be pricey.

What's needed, some experts say, is a system that aggregates and distills data into easily digestible nuggets of information for both patients and their doctors. For consumers to buy in, the interface needs to be as simple as signing into services with your Facebook account, said Guido Jouret, Cisco's Internet of Things general manager.

For Practice Fusion, the ultimate goal is to give doctors and patients seamless, on-demand data access from any device.

"If you look to 2020, there's no way electronic medical records are not running primarily in the cloud," Douglass recalls Ryan Howard, his co-founder, saying when he sold him on the idea of starting a web-based electronic health records company.

Like Google and Facebook, the San Francisco-based start-up acts as a marketplace for information. Its services are free to the more than 100,000 medical professionals who use its product. The company makes money by partnering with diagnostic labs, imaging centers and drug companies and through targeted advertising.

Practice Fusion has to play by federal rules governing patient privacy. It says all its data is aggregated and stripped of anything that would identify patients.

Privacy advocates are worried about breaches of confidentiality and possible exploitation of patients for commercial or illicit purposes.

"The big concern with services that collect or aggregate health data from multiple sources is that many of them will not be covered by health privacy laws," said Deven McGraw, the director of the Center for Democracy and Technology's Health Privacy Project. "Consequently, how they collect and use health data is going to be governed by the companies' internal privacy policies, which they write."

Bob Kocher, a partner at venture capital firm Venrock and a former special assistant to the president for health care on the National Economic Council, said data in medical records today is more secure than ever. "We lost paper charts all the time," he says. "Now we actually know which servers they're on, and we can even document if there was a breach."

Plus, he said, health data haven't yet proved all that valuable for hucksters. The bad guys don't care about your health: They want your identity, and they can piece that together from your birthday, Social Security number, e-mail and address — information they can get from a variety of sources including bank statements, he said.